Original Research

Return to Activities After Patellofemoral Arthroplasty

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Patellofemoral arthroplasty (PFA) is used to treat isolated patellofemoral arthritis, but little is known about post-PFA activity levels and functional outcome scores.

We reviewed 48 consecutive cases (39 patients) of PFAs performed between 2009 and 2014. Three validated patient-reported outcome measures (Kujala score, Lysholm score, International Knee Documentation Committee score) were used to evaluate knee function before and after surgery.

Patient-reported outcome measures were significantly improved after surgery. Return to previous preferred activity was reported by 72.2% of patients, and 52.8% of patients reported returning to the same activity level or to a higher level.

Historically, the literature evaluating knee arthroplasty outcomes has focused on implant survivorship, pain relief, and patient satisfaction. Our findings show that patients who undergo PFA have a high rate of return to their preferred activities. These findings can be used to inform patients who want to remain active after PFA.


 

References

Take-Home Points

  • PFA improved knee function and pain scores in patients with isolated patellofemoral arthritis.
  • The majority (84.2%) of patients undergoing PFA were female.
  • Regardless of age or gender, 72.2% of patients returned to their desired preoperative activity after PFA, and 52.8% returned at the same or higher level.
  • The rate of conversion from PFA to TKA was 6.3%.
  • PFA is an alternative to TKA in active patients with isolated patellofemoral arthritis.

Compared with total knee arthroplasty (TKA), single-compartment knee arthroplasty may provide better physiologic function, faster recovery, and higher rates of return to activities in patients with unicompartmental knee disease.1-3 In 1955, McKeever4 introduced patellar arthroplasty for surgical management of isolated patellofemoral arthritis. In 1979, Lubinus5 improved on the technique and design by adding a femoral component. Since then, implants and techniques have been developed to effect better clinical outcomes. Patellofemoral arthroplasty (PFA) has many advantages over TKA in the treatment of patellofemoral arthritis. PFA is less invasive, requires shorter tourniquet times, has faster recovery, and spares the tibiofemoral compartment, leaving more native bone for potential conversion to TKA. Regarding activity and function, the resurfacing arthroplasty (vs TKA) allows maintenance of nearly normal knee kinematics.

Despite these advantages, the broader orthopedic surgery community has only cautiously accepted PFA. The procedure has high complication rates. Persistent instability, malalignment, wear, impingement, and tibiofemoral arthritis progression can occur after PFA.6 Although first-generation PFA prostheses often failed because of mechanical problems, loosening, maltracking, or instability,7 the most common indication for PFA revision has been, according to a recent large retrospective study,8 unexplained pain. More than 10 to 15 years after PFA, tibiofemoral arthritis may be the primary mechanism of failure.9 Nevertheless, compared with standard TKA for isolated patellofemoral arthritis, modern PFA does not have significantly different clinical outcomes, including complication and revision rates.6Numerous patient factors influence functional prognosis before and after knee arthroplasty, regardless of surgical technique and implant used. Age, comorbidities, athletic status, mental health, pain, functional limitations, excessive caution, “artificial joint”–related worries, and rehabilitation protocol all influence function.10 Return to activity and other quality-of-life indices are important aspects of postoperative patient satisfaction.

Methods

We conducted a retrospective cohort study to describe functional status after PFA for patellofemoral arthritis. We identified 48 consecutive PFAs (39 patients) performed by a team of 2 orthopedic surgeons (specialists in treating patellofemoral pathology) between 2009 and 2014.

Three validated patient-reported outcome measures (PROMs) were used to determine preoperative (baseline) and postoperative functional status: Kujala score, Lysholm score, and International Knee Documentation Committee (IKDC) score. The Kujala score is a measure of knee function specific to the patellofemoral joint; the Lysholm score focuses on activities related to the knee; and the IKDC score is a general measure of knee function. Charts were reviewed to extract patients’ clinical data, including preoperative outcome scores, medical history, physical examination data, intraoperative characteristics, and postoperative course. By telephone, patients answered questions about their postoperative clinical course and completed final follow-up questionnaires. They were also asked which sporting or fitness activity they had preferred before surgery and whether they were able to return to that activity after surgery.

Statistical analysis included the study population’s descriptive statistics. Means and SDs were reported for continuous variables, and frequencies and percentages were reported for categorical variables. Paired t tests were used to analyze changes in PROM scores. For comparison of differences between characteristics of patients who did and did not return to their previous activity level, independent-samples t tests were used for continuous variables. Chi-square tests or Fisher exact tests were used to compare discrete variables. Statistical significance was set at P ≤ .05. All analyses were performed with SPSS Version 22.0 (IBM).

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